Roll-fed printers are a well-known type of printers. In roll-fed printers, a recording medium such as paper is wound up on an input roll and then fed into, and guided along, a path through the printer, unwinding the input roll by and by along the process. In this way, the recording medium is roll-fed (i.e. taken from a roll and fed) to a marking unit of the printer which applies a marking material (prints) onto the recording medium
Roll-to-roll printers are a common type of roll-fed printers and are characterized in that the recording medium is, after images have been printed on it, wound up on an output holder of an output roll by and by along the process.
Somme roll-fed printers comprise a cutting unit configured to cut the recording medium after images have been printed on it such that the printer does not output the entire contiguous recording medium but instead cut pieces of it.
Roll-fed printers are very efficient devices for forming a large number of images requiring a large amount of the recording medium, as the wound-up input rolls are comparatively easy to handle by both the printers and their operating personnel. Accordingly, little or no supervision by personnel is needed for roll-fed printers, especially for roll-to-roll printers, as the marked recording medium is automatically stored on the output roll.
To utilize as much of the recording medium as possible, a technique called “nesting” is commonly employed. Nesting comprises taking a plurality of individual print jobs and arranging them such in a single, larger print job comprising all of the individual print jobs. Nesting may be performed in one single direction, or in two directions. In this way, multiple individual jobs may be arranged side-by-side in a direction perpendicular to the direction the recording medium is moving along the path.
In addition, gaps left by e.g. some larger individual jobs on the recording medium roll may be filled by one or more smaller individual jobs, thus reducing the amount of recording medium used for printing the larger and the smaller individual jobs compared to printing them one after the other along the recording medium roll. Nesting therefore contributes to reduce the amount of the recording medium needed by fully utilizing both the length of the recording medium (along the direction the recording medium is moving) and the breadth of the recording medium (perpendicular to that direction of moving). Nesting is usually done before the single print job comprising the individual nested jobs is converted to a bitmap (also called a bitmap image or a raster image).
When any problems arise during the printing of the recording medium, this may result in a considerable loss of resources such as time (because the printing process might be, or might have to be, stopped until a person can solve the problems) or recording medium and marking material (because a started print job might be irreparably botched and has to be started anew).
In US 2009/0322808 A1, a method is disclosed according to which a print job currently queued as next-in-line in a printing system is only executed if and when a current amount of remaining ink in the printing system is larger than an amount required to print that print job. If that is not the case, the same procedure is performed for the print job currently queued after that print job, and so on.
In US 2012/0081726 A1, an image processing assembly is described with a print restart region that determines, upon detection of an occurrence of an abnormality during the printing operation, a print restart region starting from which a job is then scheduled to be re-printed.
In JP 2011 062954 an image forming apparatus is described which discerns guaranteed pages of a printed job and non-guaranteed pages of a printed job when a failure occurs.
In US 2016/231966 nesting of print jobs is described for saving resources when printing the print jobs.
It is desirable to have a method for controlling a roll-fed printing assembly that makes optimum use of the available resources and requires little maintenance and supervision. It is also desirable to have a roll-fed printing assembly capable of executing such a method.